The invention relates to a method of manufacturing a waveguide filter comprising two or more resonant cavities which are separated by a wall or walls in which or in each of which an iris opening is formed.
Such a method is known from German Patent Specification 1,264,634. With the known method the filter, which comprises a succession of resonant cavities, is constructed from separate plates. The plates are manufactured from a metal sheet and are subjected to a number of operations. Subsequently the plates are assembled by means of auxiliary members, a plurality of plates constituting the outer walls of the filter, after which the cavities are formed by mounting plates in which a window is formed. Then the plates are interconnected by screwed or welded joints, after which some finishing operations are performed.
It is generally known that stringent requirements are imposed on the accuracy with which a waveguide filter is manufactured. Surface irregularities in the walls of the resonant cavities and dimensional errors may lead to substantial power losses and may degrade the filter operation.
The known method, in which the required surface smoothness and the exact dimensions of the resonant cavities are obtained by subjecting the individual plates to a plurality of operations, followed by a time-consuming assembly process, has the drawback that the manufacturing time is long and the manufacturing costs are high.